Methods: In this retrospective cohort study, we included patients treated with PED from October 2010 to May 2016. A total of 39.7% (n = 158) of patients were dispensed a loading dose of 650 mg of aspirin plus at least 600 mg of clopidogrel 24 hours preceding PED deployment, compared to 60.3% (n = 240) of patients who received 81-325 mg of aspirin daily for 10 days with 75 mg of clopidogrel daily preprocedurally. The mean follow-up was 15.8 months (standard deviation [SD] 12.4 months). modified Rankin Scale (mRS) was registered before the discharge and at each follow-up visit. To control confounding, we used multivariable logistic regression and propensity score conditioning.

Results: Of 398 patients, the proportion of female patients was ~16.5% (41/240) in both groups and shared the same mean of age ~56.46 years. ~12.2% (mean = 0.09; SD = 0.30) had a subarachnoid hemorrhage. 92% (mean = 0.29; SD = 0.70) from the pretreatment group and 85.7% (mean = 0.44; SD = 0.91) of the bolus group had a mRS ≤2. In multivariate analysis, bolus did not affect the mRS score, P = 0.24. Seven patients had a long-term recurrence, 2 (0.83%; mean = 0.01; SD = 0.10) of which from the pretreatment group. In a multivariable logistic regression, bolus was not associated with a long-term recurrence rate (odds ratio [OR] 1.91; 95% confidence interval [CI] 0.27-13.50; P = 0.52) or with thromboembolic accidents (OR 0.99; 95% CI 0.96-1.03; P = 0.83) nor with hemorrhagic events (OR 1.00; 95% CI 0.97-1.03; P = 0.99). Three patients died: one who received a bolus had an acute subarachnoid hemorrhage. The mean mortality rate was parallel in both groups ~0.25 (SD = 0.16). Bolus was not associated with mortality (OR 1.11; 95% CI 0.26-4.65; P = 0.89). The same associations were present in propensity score-adjusted models.

Conclusions: In a cohort receiving PED, a 600-mg loading dose of clopidogrel should be safe and efficacious in those off the standard protocol or showing <30% platelet inhibition before treatment.